Many industrial activities employ processes that produce large amounts of wastewater that may be contaminated with species that are persistent environmental pollutants. In particular, the presence of dissolved metals in the aqueous wastewater produced by mining, chemical, pharmaceutical, and metallurgical sites, among others, present serious risks for the contamination of the drinking water supply used by humans and animals within the area of the industrial activity.
For example, arsenic is a common contaminant associated with industrial activities and is considered to represent a hazard to human health in values in excess of 0.01 mg/L (10 ppb) in drinking water. Therefore, the U.S. Environmental Protection Agency (EPA) has adopted this value (≤0.01 mg/L) as a standard for drinking water, while the World Health Organization (WHO) adopted this value as a worldwide guideline. Similarly, other dissolved metals also possess appropriate standards and guidelines. As a result of these standards, treatment of industrial wastewater is required in many areas in order to produce a treated stream of wastewater within which dissolved metal contaminants have been either completely removed or are present in levels accepted by regulatory agencies as being safe for discharge into the environment.
In addition, in regions where industrial activities were in operation prior to the implementation of standards for contaminant levels in discharged wastewater, the soil, and in turn groundwater sources, may already be compromised and contain unacceptable levels of dissolved or leachable metals and/or organic contaminants. Thus, a similar treatment may be necessary for the groundwater to be safely used as a drinking water supply or for irrigation purposes.